Generally, a mobile communication system has been developed for the purpose of providing communication while ensuring the mobility of a user. Thanks to a rapid development of technology, such mobile communication system has reached a stage capable of providing a high-speed data communication service as well as a voice communication.
In recent years, as one of the next generation mobile communication system, a standardization for Long Term Evolution (LTE) has been progressed in 3GPP. The LTE aims at commercialization by 2010, which is a technology that implements a high-speed packet-based communication having a transmission speed of maximum about 100 Mbps higher than currently available data transfer rate. To this end, various methods have been discussed, for example, a method of reducing the number of nodes positioned on a channel by simplifying the structure of network, or a method of enabling radio protocols to approach a radio channel as far as possible is under discussion.
In the meantime, in a data service unlike a voice service, resources that can be allocated is determined according to the amount of data to be transmitted and a channel condition. Therefore, a wireless communication system such as a mobile communication system performs management such as allocation of transmission resources with consideration for the amount of resource to be transmitted by scheduler, the channel condition, and the amount of data. This is also performed in the LTE which is one of the next-generation mobile communication systems in the same manner, and the scheduler located in the base station manages and allocates wireless transmission resources.
Recently, a discussion on an evolved LTE communication system (LTE-Advanced, LTE-A) that improves transmission speed by grafting various new technologies onto the LTE communication system has been started. Among the new technologies to be introduced, some technologies take a Heterogeneous Network (Hetnet) environment into consideration.
The Hetnet refers to a wireless network composed of a multi-cell i.e., cells that have various sizes and performances such as a macro cell, a pico cell, a femto cell, and the like. Such various types of cells may be organically and effectively interworked, thereby providing the best service to an user equipment. In the Hetnet environment, according to the mobility of the user equipment, a hand-over technology may be improved to obtain optimum performance, and a service area of the picocell or the femtocell may be adjusted by properly scheduling radio resources. In addition, a signal of one user equipment may be received by a plurality of base stations or a receiver to improve reception performance.